Method for saturating fibrous sheet material



. P 1946- JQ G. YOUNG METHOD FOR SATURATING FIBROUS SHEET MATERIAL Filed March 24, 1943 ATTORNEY Patented Sept. 17, 1946 METHOD FOR SATURATING FIBROUS SHEET MATERIAL James G. Young, Shreveport, La., assignor to Bird & S of Massachusetts on, inc., East Walpole, Mass., a corporation Application March 24, 1943, Serial No. 480,352

This invention relates to methods and apparatus for saturating a fibrous sheet material with a bituminous compound such as asphalt,

5 Claims. (Cl. 117-115) In the manufacture of roofing material and the like, wherein a fibrous material, usually felt, is saturated with asphalt, conventional saturating practice late apply the asphalt simultaneously uniformly to both surfaces of the felt by dipping or floating acontinuously moving strip of the basarnaterialiin'ja bath of hot asphalt.

In this practicegdifliculty is often experienced 5 with excessive foamii ig of the asphalt in the bath and on the material, produced by air and moisture escaping from the felt as the asphalt penetrates into it, which interferes with the saturation, causes loss of asphalt by overflow and necessitates a slowing down of the saturating process to an undesirably slow rate. The extent of this foaming depends upon the moisture content of the material which varies with atmospheric conditions, nature of the material, etc., and also upon the character of the asphalt, asphalts of low surface tension characteristics such as certain mid-continent asphalts being particularly subject to foaming.

In order to overcome this difliculty it has been proposed to saturate the material by applying the asphalt to one side only through the medium of sprays or applicator rolls, leaving the other side of the material exposed to the atmosphere. In this method moisture and air are free to escape from the exposed side of the material and foaming is thus prevented. This advantage is, however, counterbalanced by certain disadvantages. It is diflicult to apply asphalt in this manner and to obtain therewith a thorough, even saturation of the material by the asphalt, particularly at the edges of the material. Moreover, as this method requires theasphalt to strike entirely through the material, saturation takes place slowly and is less complete on the side of the material away from the sprays or applicator rolls.

The object of this invention is to provide a novel method and apparatus for saturating a fibrous material or felt with bituminous compound by which these and other diiliculties of prior practices are eliminated and a more thorough, even and rapid saturation of the material is produced.

According to the method of the invention, hot bituminous compound is initially applied to one surface of the fibrous material or felt in spaced areas only, leaving intervening areas of the surface uncoated with the compound. The material is then exposed to atmosphere for an interval during which the hot compound on the coated areas of this surface penetrates to the interior of the material beneath these areas, driving moisture therefrom laterally into the untreated areas from which its escape to atmosphere is unimpeded. More of the compound is then applied to this surface of the material in a manner to substantially completely coat the untreated areas of the surface. This is preferably by one or more spaced spot applications, such as the initial application, to previously untreated areas of the surface, so that the extent of these areas is progressively reduced, there being an interval of exposure of the material to atmosphere between each said application to permit the escape of moisture from yet untreated areas of the surface. The surface may be given a final, complete coating of the compound if desired.

During or after the above mentioned process of applying the compound to one surface of the material, its opposite surface is also treated with the compound. This treatment may be one or more spaced spot and/or stripe applications, or may be one or more complete coatings of the compound. Preferably, however, a complete coating of the compound is applied to this surface of the material simultaneously with each spot application to the other surface. During intervals of exposure of the material between applications, the compound of the coatings pene trates the material, driving the moisture to the untreated areas of the material from which it freely escapes to the atmosphere.

By means of this process I am enabled efiectively to expel the moisture from the material without production of excessive foaming, Impregnation takes place from both surfaces of the material. is more thorough, uniform and rapid than that produced by a process in which the compound is applied to one side only of the material and which requires penetration of the compound entirely through the material to effect saturation.

An important practical advantage of the process is that it can be performed by dipping the material directly in asphalt and the invention provides novel apparatus for so practicing the process. In the accompanying drawing, which illustrates a preferred embodiment:

Fig. 1 is a diagrammatic sectional view of the apparatus;

Fig. 2 is a front elevation of one of the dip Fig. 3 is a vertical section in the line 3-3 of Fig. 2.

In Fig. 1 of the drawing. a conventional dip tank is shown at III which is supplied by means not shown with hot asphalt kept at a constant level determined by the height of an overflow gate l2. The asphalt may be kept at any temperature suitable for saturating, around 450? F. being preferable, and to this end the tank is heated by steam pipes or the like (not shown).

The strip i l of felt or the like, withdrawn from a suitable source (not shown) such as a freely rotatable supply roll, is passed alternately over dip rolls l6 and forwarding rolls l8 located above and between the dip rolls, there being four dip rolls and four forwarding rolls in the embodiment illustrated. Each of the dip rolls has its axis disposed above and close to the surface of the asphalt in the dip tank and so that a small lowermost portion of the roll surface is below the surface of the asphalt in the dip tank. The rolls II are located considerably above the dip rolls l6 and are so arranged that the felt engages and. leaves the surface of dip rolls It at points considerably above the level of asphalt in the dip tank, and is held under sufficient tension to press its upper surface tightly to the surface of rolls it While it is carried below the surface of the asphalt. Exposure of the roll-engaging surface of the felt to the asphalt during the dipping is thus prevented except in areas registering with the roll apertures.

Referring to Figs. 2 and 3 of the drawing, it will be seen that the dip rolls l6 are hollow cylinders attached by spokes 20 to shaft 22 which are rotated by suitable drive mechanism (not shown). Each of the rolls I6 is provided with a plurality of apertures 24 therethrough which, as shown, are arranged in longitudinal rows, the apertures of successive rows being relatively longitudinally offset. As shown in Fig. v3, the ends of the rolls I6 are open, permitting asphalt to flow into the interior of the rolls to the level of asphalt in the dip tank surrounding the lower portion of the rolls. As each roll rotates, the apertures 24 of successive rows are carried below the level of asphalt'in the dip tank and within the roll, so that asphalt within the roll flows by gravity through the apertures onto the upper surface of the felt and penetrates therein toward the asphalt penetrating the opposite side of the felt, forming saturated spots conforming in ar-- rangement to, and slightly larger in size than, the apertures 20. The underside of the felt is, of course, fully exposed to the asphalt in the tank as it is carried around the dip rolls.

As the felt leaves the first dip roll H (at the left of Fig. 1), it is thus completely coated on its under side with asphalt and its upper side carries spaced spots of asphalt. The relatively long carry over the adjacent forwarding roll i8 to the next dip roll i6 permits this asphalt to penetrate .toward the interior of the felt, driving moisture from the upper side of the felt between the asphalt coated spots where its escape to the-atmosphere is unimpeded. Preferably, the forwarding rolls l6 are heated to prevent solidifying of the asphalt while the felt is traveling between dip rolls.

This process i repeated as many times as there are pairs of dip rolls and forwarding rolls,- four in the illustrated embodiment. The arrangement is such that the apertures of each roll do not register with the same areas of the felt as those of the preceding roll or rolls. To this end the apertures of each roll may be laterally offset relative to corresponding apertures of a preceding roll or rolls, although-this is not necessary as registry of the apertures 01' two rolls with the same areas of the felt is not likely to occur unless the parts were intentionally proportioned and arranged to produce registry.

llhe spots of asphalt applied to the upper side of the felt by each dip roll are therefore between the spots applied during passage of the felt over a preceding dip roll or rolls. Thus the untreated areas'on the upper side of the felt are progresively reduced in area, as the quantity of moisture to be driven ofl through them is reduced, both by the successive spot applications of asphalt thereto and by penetration of asphalt from the under side of the felt which is being repeatedly fully exposed to the asphalt.

After leaving the last of the dip rolls IS, the felt may be batched in usual manner, or may be floated or otherwise dipped again in asphalt.

I have obtained excellent results with apparatus as shown, in which the four dip rolls It had a diameter of 10 inches, the aperture 24 were inch in diameter, the apertures of "each row were spaced apart 10 inches longitudinally of the roll, and the radially aligned pairs of apertures of alternate rows were spaced apart 5 inches circumferentially of the rolls. A final float dip in asphalt was given the felt after it left the last dip roll. No foaming difliculties 'were encountered during the roll clips or the float dip, although the conditionsoi the asphalt and felt were such that terial with the compound while simultaneously coating spaced areas only of the opposite surface of the material with the compound, exposing'said last named surface of the material to atmosphere to permit escape of vapors from the uncoated areas thereof, and thereafter applying the compound to said. uncoated areas.

2. A method for saturating a fibrous sheet material with hot bituminous compound which comprises applying successive coatings of the compound to the entire surface of one side of the material, during the application of each said successive coating applying the compound, at spaced interval only, to uncoated areas of the opposite surface of the material thereby progressively reducing the area of the uncoated portions of said last named surface, and between said coating steps exposing said last named surface of the material to atmosphere to permit escape of vapor from the uncoated portions thereof. 3. A method for saturating a fibrous sheet material with hot bituminous compound which comprises intermittently immersing the material in the compound in a manner to expose one of the surfaces of the material repeatedly entirely to the compound and simultaneously to expose the other surface of the material in successively different spaced areas only to the compound, and

between said immersions exposing the material to atmosphere to permit escape of vapors from the portions of said last named surface of the material between said spaced areas thereof.

- 4. A method for saturating a fibrous sheet material with hot bituminous compound which com-- atmosphere to permit escape .of vapors from the portions of said last named surface of. the material between said spaced areas thereof, and thereafter immersing the material in the compound "tween said immersions exposing the material to in a manner to expose the entire area of both surfaces of the material to the compound.

5. A method for saturating a fibrous sheet material with hot bituminous compound which comprises immersing the material in the compound in a manner to expose one entire surface of the material and simultaneously spaced areas only of the other surface 'of the material to the compound, thereafter exposing the material to atmosphere to permit escape, of vapors from theportions of said last named surface of the material between said spaced areas thereof, and thereafter re-immersing the material in the compound in a manner to expose the entire area of both surfaces to the compound. v

JAMES G. YOUNG. 

